``Magne-Blast´´ Air Circuit Breaker for 5,000-Volt Service

Fundamental principles of magnetic action and thermal reaction have been united in an original manner to create a new circuit interrupter, the ``Magne-Blast´´ air circuit breaker. Intended for general applications in switching, controlling, and protecting 2,300- to 5,000-volt circuits, this breaker, throughout a comprehensive test program, has proved satisfactory in every requirement. An open presentation of test results shows how an efficient arc chute functions thermally to decay and extinguish the arc with a minimum of voltage disturbance. The breaker is immune to circuit recovery characteristics. Principles of performance are discussed using the familiar terms of current, voltage, resistance, and reactance in showing their effect on the instantaneous values of phase angle, current reduction, and the attendant rates of rise of recovery voltage. The coordinated electrical and mechanical design is described in some detail and a typical arrangement is shown as used in a metalclad equipment.